Introduction to the Chest X-ray

Question 1

Why are chest X-rays important?

Answer 1

Still the most commonly performed imaging test

Question 2

Meaning of PA view?

Answer 2

Posterior anterior view (X-rays pass from POSTERIOR TO ANTERIOR): Patients stands 2m away from X-ray apparatus, facing the casette, with their shoulders braced forwards (so that the scapulae do not obscure the lungs) Radiograph is taken at FULL INSPIRATION

Question 3

Benefits of PA radiograph?

Answer 3

As the heart lies anteriorly within the thorax, PA views minimises magnification of the cardiac shadow (X-rays come from point source and diverge)

Question 4

When is AP view used?

Answer 4

With patients who cannot stand and using mobile x-way apparatus on wards; the casette is placed behind the patient and X-rays pass from ANTERIOR TO POSTERIOR

Question 5

Benefits of AP radiograph?

Answer 5

Can be lifesavers in very unwell or bed-bound patients

Question 6

Which is superior, AP or PA view, and explain why?

Answer 6

AP radiographs technically inferior to PA as: Heart shadow is magnified, so heart size cannot be assessed accurately Scapulae overlie and partly obscure lungs Can be difficult for patient to take an adequate inspiration

Question 7

Limitations of chest X-rays and alternatives?

Answer 7

2-D depictions of 3-D structures So, lateral view can be used to give some addition information but used less commonly, due to increased availability of CT scans

Question 8

Before analysing a chest X-ray, what should be done?

Answer 8

Check patient’s name, CHI and the date of the scan Is there a side marker on the chest X-ray - is it correct? Is it technically accurate? Consider ations: Inspiration (5 ribs should be seen anteriorly) Rotation (medial ends of clavicles should be equidistant from the spinous process of the upper thoracic vertebrae) Penetration (is there enough radiation?)

Question 9

Why are ations important?

Answer 9

A poorly inspired or rotated chest X-ray can simulate pathology when none is there

Question 10

Normal structures seen on a chest X-ray?

Answer 10

Heart Great vessels Pulmonary hila Trachea and bronchi Lungs Pleura and pulmonary fissures Diaphragm Bones

Question 11

What are the hila?

Answer 11

Junctions between the heart and lungs, where the pulmonary arteries and bronchi enter and the pulmonary veins exit the lungs (lung roots)

Question 12

Importance of hila on a chest X-ray?

Answer 12

Common place for bronchial carcinomas to arise and because lymph nodes located there may become visibly enlarged due to disease

Question 13

Difference between the anatomical relationship the right and left main bronchus have with the hila

Answer 13

Different as the normal left hilum lies superiorly to that on the right (evident on a chest X-ray)

Question 14

Trachea and bronchi on a chest X-ray?

Answer 14

Normal trachea is visible on a chest X-ray but major and minor bronchi are poorly shown (unless calcified, as may occur in the elderly)

Question 15

Lung lobes?

Answer 15

Right lung - 3 lobes Left lung - 2 lobes Separated by pleural fissures (often visible on a chest X-ray)

Question 16

Describe the diaphragm’s appearance on a chest X-ray

Answer 16

On a normal chest X-ray, the right hemidiaphragm appears ~1.5 cm above the left hemidiaphragm Major deviations form this usually indicate disease

Question 17

Disease that might cause diaphragm elevation

Answer 17

Liver disease Intra-abdominal disease

Question 18

Problems causing diaphragm depression?

Answer 18

Problems within the thorax

Question 19

What do the arrows indicate?

Answer 19

Question 20

Where do the arrows point to?

Answer 20

Question 21

Where are the arrows pointing?

Answer 21

Question 22

How do the retrosternal and retrocardiac spaces appear on a chest X-ray?

Answer 22

Should be dark, normally; if they are not, disease is present

Question 23

Disease that can be detected on a chest X-ray?

Answer 23

Common disease include:

Pneumonia

Lobar collapse

Features of cardiac failure

Pneumothorax

Pneumomediastinum

Thoracic malignancy

Question 24

Describe many lung disease in relation to the “Silhouette sign”

Answer 24

On a chest X-ray, the outline of a structure can only be discriminated from its neighbour if it has a different radiographic density

Many lung disease cause an increase in lung density; if dense, disease lung abuts the heart or diaphragm, the outline/silhouette of that structure cannot be seen , as it shares the same density as the diseased lung

Question 25

Why is the silhouette sign useful?

Answer 25

Allows determination of which part of lung is disease

Question 26

What happens in pneumonia?

Answer 26

Airspaces are filled by inflammatory exudate and affected lung tissue becomes of soft tissue density; silhouette sign can be used to determine which region of the lung has been affected

In lingular pneumonia, lingular segments of the left upper lobe abut the left heart border; so left heart border becomes obscured

Question 27

Describe lobar collapse, when it occurs, causes and pathology

Answer 27

Occurs when there is an obstruction of a lobar bronchus; causes include tumours, aspirated foodstuffs, mucous impaction, etc

Lobe supplied by an obstructed bronchus is no longer ventilated and its air gets resorbed; affected lung loses volume and starts to collapse

Collapsed lung’s density increase and adjacent major fissue is dragged out of its position (each lobe has a predictable chest X-ray appearance when collapsed)

Question 28

Left upper lobe collapse pattern?

Answer 28

Left oblique fissure is pulled anteriorly (a well defined lobar edge becomes visible on the lateral view)

Collapse lobe abuts the left heart border, which becomes obscured on the PA view

Other PA signs include attenuation of X-ray beam, throughout much of the left hemithroax (seen as a veil-like opacity and reduced left lung size)

Question 29

Appearance of bronchial malignancy?

Answer 29

Both primary lung tumours and metastases are common

Metastases often appear as multiple nodules; primary tumours may present with bronchial collapse, or as a discrete mass

Look for enlarged lymph nodes and areas of focal bone destruction, indicating skeletal damage

Question 30

When is the pleural cavity visible on a chest X-ray?

Answer 30

Potential space and is only visible on chets radiographs when filled with FLUID (PLEURAL EFFUSION) or AIR (PNEUMOTHORAX)

Dense pleural fluid often seen to collect at lung bases and often forms the curved appearance of a MENISCUS at the lung edges

Pleural fluid may track into the oblique and horizontal fissures

Question 31

How does a pneumothorax occur and consequences?

Answer 31

Usually follows spontaneous rupture of the visceral pleura, allowing are to rush in from lungs every time the patient inspires

Pleural air can accumulate in this way, impairing respiratory function

Question 32

Appearance of a small pneumothorax?

Answer 32

Look for a dark crescent withour lung marking bounded medially by the lung edge (often at lung apex)

Question 33

Reason causing a pneumothorax?

Answer 33

May be a complication of a medical procedure, such as insertion of a cardiac pacemaker

Termed iatrogenic

Question 34

Types of pneumothorax?

Answer 34

Tension pneumothorax

Spontaneous pneumothorax

Question 35

Consequences of a tension pneumothorax?

Answer 35

If pneumothorax accumulates large amounts of air, it will squash lungs so patietn cannot ventilate them

Question 36

Treatment for a tension pneumothorax?

Answer 36

Medical emergency and must be DRAINED immediately

Question 37

Examples of lines and tubes inserted by doctors that often appear on and are important in chest X-rays?

Answer 37

Endotracheal (ET) tubes

Nasogastric tubes

Central venous lines

Chest X-rays used to confirm correct placement of these devices and to detect complication, such as iatrogenic pneumothorax

Question 38

Correct positioning of ET tube?

Answer 38

Tip of ET tube should be positioned about 2 cm proximal to the carina

Question 39

Which lung is a foreign body, like a tube, more likely to pass into and why?

Answer 39

Right main bronchus rather than left, as there is a more soctuse angle between trachea and right main bronchus (straighter)

Question 40

Why are previous exams useful?

Answer 40

Comparing previosu exams to current exams is useful to confirm if an abnormality if new or longstanding

In general, new abnormalities need treatment and old ones do not